Biomass pretreatment process

Abstract

A process is described for pretreating lignocellulosic biomass. The process comprises swelling the lignocellulosic biomass with an aqueous liquid. The pretreated lignocellulosic biomass may be used as a feedstock for the enzymatic conversion to ethanol, or in a thermal conversion. process to produce bio-oil. The pretreatment results in a greater yield and, in the case of a thermal conversion process, a better quality of the bio-oil. The pretreatment process may be used to adjust the composition and amount of inorganic material present in the lignocellulosic biomass material.

1. A process for pretreating a lignocellulosic biomass material for conversion to bio-oil, said process comprising:
 (i) contacting the lignocellulosic biomass material with an aqueous fluid, to form a swollen solid lignocellulosic biomass; 
 (ii) dewatering the swollen biomass to form a solid modified lignocellulosic biomass material having an increased bulk porosity; and 
 (iii) subjecting the solid modified lignocellulosic biomass material to enzymatic hydrolysis, thermoconversion, or combinations thereof. 
 
     
     
       2. The process of  claim 1  wherein the step of contacting the lignocellulosic biomass with an aqueous fluid is carried out at an elevated temperature in the range of from 35° C. and 100° C. 
     
     
       3. The process of  claim 1  wherein the step of contacting the lignocellulosic biomass with an aqueous fluid is carried out at an elevated temperature that is greater than 100° C. and is carried out under autogenous pressure. 
     
     
       4. The process of  claim 1  further comprising subjecting the solid modified lignocellulosic biomass material to drying, milling, comminuting or combinations thereof. 
     
     
       5. A pre-treatment process for preparing a lignocellulosic biomass material for conversion to a bio-oil, said pre-treatment process comprising the steps of:
 (i) swelling the biomass material with a solvent, optionally aided by pH control, application of mechanical action, the incorporation of additive(s) and temperature control; 
 (ii) removing solvent from the swollen solid biomass material by applying mechanical action to the solid biomass material to form a solid modified lignocellulosic biomass material having an increased bulk porosity; and 
 (iii) subjecting the solid modified lignocellulosic biomass material to enzymatic hydrolysis, thermoconversion, or combinations thereof. 
 
     
     
       6. The pre-treatment process of  claim 5  wherein the solvent is an aqueous liquid. 
     
     
       7. The pre-treatment process of  claim 5  wherein the mechanical action results in a particle size reduction of the biomass material and is exerted by equipment selected from the group consisting of high shear mixers, kneaders, colloid mills, planetary mixers, mix-mullers, extruders, pressure filters, centrifuges and/or ball mills or other comminuting equipment. 
     
     
       8. The process of  claim 5  wherein the ash content of the biomass material is reduced to less than 5 wt %, based on dry weight of the biomass material. 
     
     
       9. The process of  claim 5  wherein Fe content of the biomass material is reduced to less than 2,000 mg/kg, based on dry weight of the biomass material. 
     
     
       10. The process of  claim 5  wherein the solvent of step (i) comprises an inorganic acid or an inorganic base. 
     
     
       11. The process of  claim 5  comprising the additional step of adding an inorganic catalytic material before subjecting the solid modified lignocellulosic biomass material to enzymatic hydrolysis, thermoconversion, or combinations thereof. 
     
     
       12. The process of  claim 11  wherein the inorganic catalytic material is dissolved in a solvent. 
     
     
       13. The process of  claim 12  wherein the solvent is an aqueous liquid. 
     
     
       14. The process of  claim 13  wherein the catalytic material comprises an inorganic salt. 
     
     
       15. The process of  claim 14  wherein the catalytic material comprises a cation selected from the group consisting of K, NH 4 , Na, Ba, Mn, Mg, Ca, Li, Zn, and mixtures thereof. 
     
     
       16. The process of  claim 15  wherein the catalytic material further comprises an anion selected from the group consisting of OH, CO 3 , SO 4 , PO 4 , Cl, NO 3  and mixtures thereof. 
     
     
       17. The process of  claim 14  wherein the catalytic material comprises an insoluble inorganic material, in a colloidal or nanoparticular form. 
     
     
       18. The process of  claim 17  wherein the insoluble inorganic material is selected from the group of refractory oxides, zeolites, cationic clays, anionic clays, layered hydroxide materials, hydrotalcites, and mixtures thereof. 
     
     
       19. The process of  claim 5  wherein the thermoconversion process is selected from the group consisting of pyrolysis, catalytic cracking, gasification, steam gasification, hydrotreatment, and combinations thereof. 
     
     
       20. The process of  claim 19  wherein thermoconversion process is carried out in a fixed bed reactor, a fluidized bed reactor, fluidized catalytic reactor (FCC), or an ebbulated bed reactor.